Asked how the SNP would exploit a hung parliament, he said: "Our job would be to progress Scottish interests and that, in particular, means to enforce the delivery of the vow, the promise that was made to Scotland of home rule, neo-federalism, devo to the max, in these last desperate days of the referendum campaign where these three Westminster leaders were in a state of panic.

"These promises will have to be redeemed."

He added: "Instead of another bout of austerity from Labour or Conservative the cancellation of the renewal of the Trident missile system and diverting that funding, £30 billion over the next ten years, into health and education and something useful and productive and I think that will have a lot of support in England as well as in Scotland."

Asked about a Conservative campaign poster that has his head photoshopped on to the body of shadow chancellor Ed Balls, he said: "I was pretty annoyed about the photoshopping on Ed Balls' body. That was certainly below the belt."